Segmental grinding wheel



alt d1 29, 1928. 3,663,310

w. T" M AULAY SEGMENTAL GRINDING WHEEL Filed July 15, 1923 fwdw MATTORNEYS Patented Mar. 20, 1928. UNITED STATES PATENT orrlcs.

WILLIAM '1'. MAOAULAY, OF BROOKLYN, NEW YORK, ASSIGNOR TO THECABBOBUNDUI- COMPANY, OENIAGABA FALLS, NEW YORK, A CORPORATION OFPENNSYLVANIA.

SEGHENTAL GRINDING WHEEL.

Application filed July 13,

The present invention relates broadly to grinding wheels, and moreparticularly to inding wheels ofithe segmental type used or planesurface grinding. i

In grinding plane surfaces it is usual to use a cylindrical wheel, thethickness of the cylinder being much less in a radial direction than in,an axial direction, and the grinding being done on the face of the Wheelnormal to its axis. This form of grinding wheel is very largely used inthe surfacing of iron, steel and metal parts. In the use of these wheelswhere there is a large part of the working surface of the wheel incontact with the work being ground, the most important desideratum is afree cutting wheel which will not glaze or gather metal particles on itsface, and which will not burn or leave chatter marks on the work ground.It is therefore usual to employ wheels of the softer grades. The bondholding the abrasive grains in wheels of soft grades being of lowtensile strength, these wheels. are

fragile and require careful handling in mounting and in use. They arealso easily broken in transportation.

I have discovered that this operation of plane surface 'ndin can be veryeconomicall and satlsfactori y carried out by employmg this cylindricalshape of wheel in the form ofsegments instead of a solid wheel, b reasonof the fact that in a wheel in the orm of segments, whether thesegments, are set with a space between them or are set together withends touching, the break in the! contact surface supplies clearancespaces and this promotes the free and rapid cutting qualities of thewheel and avoids glazing, giving results not attainable with thesolid;cylindrical wheel. Moreover se ments are cheaper to produce than asolid wheel, because the labor of moldin' and burning smaller pieces isvery muc less, and they can be handled without danger of breakage;

A serious difiiculty involved in the use of the segmental typeofgrinding wheel for this purpose, however, is to provide a satisfactorymounting for the segments owing to their fragile nature and to thetendency of centrifugal and other forces to unseat them.

By the present invention I have provided a form of mounting particularlysuitable for this type of wheel, and whereby the 1923. Serial No.651,350.

n the accompanying drawings, I have shown, for purposes of illustrationonly, certain embodiments of my invention, it being understood, however,that the drawings do not define the limits of the invention, as changesmay be made in the construction therein disclosed without departing fromthe spirit of my invention or scope of my broader claims.

In the drawings:

Figure 1 is a vertical sectional view through a segmental grinding wheelembodyin%my invention;

igure 2 is a bottom plan'view of the wheel shown in Figure 1;

Figures 3 and 4 are plan views, and

Figures 5 and 6 are sectional views illustrating modified forms ofsegments.

Referring to Figures 1 and'2, there is illustrated a grinding'wheelcomprising a metallic face plate. 1 mounted upon a shaft 2. Detachablymounted upon the under side of the periphery of this face plate byscrews 4 is a metal ring-3. The ring is provided with: an annularchannel 5 therein, formed by inner and outer flanges having undercutwalls, whereby the channel has a dovetail form in cross section. Aplurality of segments 6 are seated in the channel. The sides of theportions of the se ents which are seated in the channel may recessed togive the base portions of the segments a dovetail cross sectional formalso. The-spaces between the sides of the base portions of the segmentsand the undercut walls of the flanges of the ring are filled with asuitable cement, such as sulphur. The walls of the flanges of the ring,instead of bein undercut, may have vertical sides left roug as they comein casting, in which case the cement .is often sufiicient to hold thesegments in case, however, I emplo segments 3" or more in hei ht, 'Ireferab y secure a thin steel band a ut 1 wide and thick around theperiphery of the segments. This band is provided with a clamping andadjusting screw 8, which should be tightened 'just enough to hold theband in place. This.

band is spaced from the ring 3 and assists in holding the segments inplace against centrifugal force tending to unseat them, and acts as asafety guard in case a segment should break. The band should be locatedabout from the cutting face of the segments, and as they wear away, itshould be adjusted toward the ring.

When the wheel is put inuse and brought up to working s eed, there is ahigh centrifugal force ten ing to throw the segments outward in a radialdirection and cause the outer ed e of the base of each se out to bearagainst the outer flange of t e channel. This results in a tendency ofthe seg ments to tip up,that is, there IS a tendency for the innerbottom edge of each segment to rise. This is overcome by means of theinner flange having the undercut wall. This undercut wall cooperateswith the inneredge of the base ofeach segment and the-cement thereon tohold'the segments rigidly to their seat in the channel against thecentrifugal force tending to unseat them. The torsional strain on thesegments in the act of grinding also tends to pull the segments out ofthe channel, and this strain is likewise opposed and met b thearrangement of the undercut flanges between which the segments arecemented.

Another marked advantage of this type of construction is that it ispossible to assemble a number of rings with various grades of segments,and change the grinder from one grade to another by simply detaching thering with its set of segments of one particular grade and replacing itwith another ring having segments of a different grade.

In comparing the relative elhciency of my segmental wheel with asolidwheel, I find that the time of grinding a given piece of work is reduced10 to 15 per cent and upwards, and on the general run of work, such aslarge and small pieces of hard and soft steel, torgings and the like, aset of segments will last approximately 50 per cent longer than anequivalent-length of a solid wheel. For the general run of work thesegments may be set in contact with no spacing, but on bread surfaces 6square or over, it is better to space the segments, using in the exampleI have cited ten or eleven segments in place of twelve segments, asthese spaces between the segments greatly cut down the tendency toglaze.

In Figure 3 l have shown'a modified form of segment in which the endslap one against the other while maintaining an open space between thesegments in a peripheral direction. This results in a more rigidconstruction which prevents some vibration and has advantages ingrinding certain classes of work.

In Figure 4 ll show a modified form of segment in which the ends arelocked by a tongue and groove design.

lnFigure 5 ll show a modified form of a segment in which there is ataper from the top of the segment to the bottom, the rinding face beingnarrower than the base, T have found that as the segment wears down, itis possible to use a wider face, that is a wider inding surface, andmaintain the same rigidity and the same freedom from vibration, and thisis accomplished by the tapered form, because when the segment is new andthe rinding face is at some distance from the ase of the segment whereit is held in the ring, the face is comparatively narrow and getswiderjas the segment wears down and the necessity for rigidity becomesless.

It will be noted in this form also that the distance across the base ofthe segment from a to b is [greater than the width of the opening in thering from o to d. The segments are inserted by first tipping up eachsegment and bringing the point 0; thereof to the point e in the bottomof the channel of the ring, then the segment can be seated in thechannel, as the point I) of the segment will clear point d of the ring.

In Figure 6 I show a segment having straight sides but with the sameproportioning of the base of the segment to the width of the opening asin the Figure 5 construction.

Another important advantage of the present invention arises from theprovision of the channel in the metal base plate having a dovetail formin cross section for cooperation with segments having bases with a'similar cross sectional form, whereby the segments are securely held inplace against the centrifugal force tending to unseat them.

I claim: H

1. In a segmental grinding wheel, a flanged center disk, a ring memberon the flange whose diameter is substantially the same as the diameterof the central ortion of the disk, the ring and disk having contactingshoulders by means of which the ring is centered on the flange of thedisk, means for securing the ring to the disk, a channel in the face ofthe rin at the side opposite the contacting shoul ers and a plurality ofgrinding'sections in the channel.

2. In a grinding wheel, a ring having a channel in the facethereof ofinwardly increasing width, segmental grinding stones in the ring havingbase portions of inwardly increasing width, the greatest width of thebase portions of the stones being no greater than the narrowest portionsof the channel so that the sections can be inserted in the channel, anda solid filling material filling the voids between the undercut sides ofthe channels and the expanded base portions of the se8ments.

reee eio a 3. In a grinding Wheel, a ring having a narrowest porfiionsof the channel so that channel of dovetailed cross-section in the thestones can be set in and removed from 10 face thereof, a plurality ofsegmental grindthe ring, and filling material poured around ing stonesset into the channel, said stones the base of the stones and filling thechan- 5 having base portions received in the channel for retaining thestones in the channel. nels which are of dovetailed cross-section, Intestimony whereof I have hereunto set the maximum Width of the baseportions my hand, of the stones being no greater than the WILLIAM T.MAGAULAY.

